I can not solve this out, i keep getting the wrong answers

Question

11% compounded every 2 months for 4 years.

a) The annual interest rate as a decimal is -

b) The number of compounding periods per year is -

c) The number of years is -

d) The total number of compounding periods are -

Answer 1

General formula is

A=P(1+r/n)^nt

where n= number of compounding periods per year = 6 if it's compounded every 2 months.

t = number of years = 4

r = rate of interest = 11% = .11

P = beginning amount at time t=0

A = ending amount, at the end of 4 years

A=P(1+.11/6)^6(4)

A =P (1.018333...)^24

total number of compounding periods in one year = 6

total number over 4 years = tn = 4x6 = 24

doubling time is when the investment doubles in amount

2 = (1.018333...)^6t, solve for t

or use that formula to find how much is left, what A is, when you know what P is.